Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/003—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor characterised by the choice of material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/006—Pressing and sintering powders, granules or fibres
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
  • C08J3/124—Treatment for improving the free-flowing characteristics
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08L27/18—Homopolymers or copolymers or tetrafluoroethene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
  • B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
  • B29K2027/18—PTFE, i.e. polytetrafluoroethylene, e.g. ePTFE, i.e. expanded polytetrafluoroethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/25—Solid
  • B29K2105/251—Particles, powder or granules
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/26—Scrap or recycled material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0018—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular optical properties, e.g. fluorescent or phosphorescent
  • B29K2995/0022—Bright, glossy or shiny surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0037—Other properties
  • B29K2995/0077—Yield strength; Tensile strength
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2427/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2427/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2427/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08J2427/18—Homopolymers or copolymers of tetrafluoroethylene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group

Definitions

• the present invention relates to a fluororesin molded article.
• Polytetrafluoroethylene resin (molding powder) obtained by suspension polymerization of tetrafluoroethylene (TFE) is compression molded and then sintered to form a molded body.
• the molded body obtained by sintering is processed into a molded product of a desired shape by cutting or the like.
• tetrafluoroethylene resin sintered PTFE
• cutting waste generated during processing is hard and does not hold together even when compressed after crushing, making it impossible to mold. For this reason, it has been difficult to reuse it.
• Patent Document 1 describes how, when sintered PTFE powder is mixed with a PTFE dispersion (unsintered PTFE dispersion) obtained by emulsion polymerization of TFE, compression molded, and sintered to produce a molded body, the porosity after sintering decreases and the tensile strength after sintering increases as the mixing ratio of unsintered PTFE increases. For example, it describes an example in which the porosity after sintering becomes 0% when the mixing ratio of unsintered PTFE is 100%.
• the present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a fluororesin molded article using a fluororesin having a thermal history of being heated to or above its melting point, which has good compressive strength and compressive creep resistance.
• the first fluororesin is a non-melt-formable fluororesin
• the second fluororesin is a non-melt-moldable fluororesin produced by emulsion polymerization
• a ratio of the first fluororesin to a total mass of the first fluororesin and the second fluororesin is 40 mass% or more;
• the gloss of the molded article at an incident angle of 60° is 15% or more.
• a fluororesin molded product is obtained using a fluororesin that has a thermal history of being heated to above its melting point, and has good compressive strength and compressive creep resistance.
• unit based on a monomer is a general term for an atomic group formed directly by polymerization of one monomer molecule and an atomic group obtained by chemically converting a part of the atomic group.
• a unit based on a monomer is also simply referred to as a monomer unit.
• “Monomer” means a compound that has a polymerizable carbon-carbon double bond.
• “Melting point” means the temperature corresponding to the maximum of the melting peak as measured by differential scanning calorimetry (DSC).
• DSC differential scanning calorimetry
• average particle size refers to the 50% integrated value (median diameter, D50) in the number-based particle size distribution determined using a laser diffraction/scattering particle size distribution analyzer (for example, LA-920 measuring instrument manufactured by Horiba, Ltd.).
• melt-formable it is meant that the material exhibits melt flowability.
• Exhibiting melt fluidity means that there exists a temperature at which the melt flow rate is 0.1 to 1000 g/10 min under a load of 49 N at a temperature at least 20° C. higher than the melting point of the resin.
• Melt flow rate means the melt mass flow rate (MFR) as defined in JIS K 7210:1999 (ISO 1133:1997).
• non-melt moldable means that the material does not exhibit the melt flowability.
• SSG Standard specific gravity
• Glossiness is a value that serves as an index of glossiness, and is the value of specular glossiness at an incident angle of 60° measured in accordance with JIS Z 8741.
• the fluororesin molded article of the present invention is a molded article obtained by compression molding and sintering a fluororesin composition containing fluororesin 1 (hereinafter also referred to as "fluororesin 1") and fluororesin 2 (hereinafter also referred to as "fluororesin 2"). Both fluororesin 1 and fluororesin 2 are non-melt-formable fluororesins.
• the fluororesin 1 and the fluororesin 2 may be the same as or different from each other.
• the fluororesin 1 and the fluororesin 2 may each independently be one type of fluororesin or two or more types of fluororesin may be used in combination. When two or more types of fluororesin are used in combination, it is sufficient that the mixture of the two or more types of fluororesin is non-melt moldable.
• TFE units polymers having tetrafluoroethylene units
• examples thereof include polytetrafluoroethylene (PTFE), tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, tetrafluoroethylene-chlorotrifluoroethylene copolymer, tetrafluoroethylene-ethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.
• PTFE polytetrafluoroethylene
• tetrafluoroethylene-ethylene copolymer tetrafluoroethylene-hexafluoropropylene copolymer
• tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer
• fluororesin 1 and fluororesin 2 are each independently PTFE.
• the content of TFE units in PTFE relative to the total mass of the fluororesin is preferably 99 mass% or more.
• the content of TFE units in PTFE relative to the total mass of the fluororesin is more preferably 99.5 mass% or more, and may be 100 mass%.
• Monomer units other than TFE units include the above-mentioned ethylene units, hexafluoropropylene units, perfluoro(alkyl vinyl ether) units, chlorotrifluoroethylene units, vinylidene fluoride units, as well as monomer units based on perfluoro(2,2-dimethyl-1,3-dioxole), perfluoro(4-methoxy-1,3-dioxole), perfluoroalkylethylene, etc.
• the monomer units other than TFE units may be of one type or of two or more types. By including monomer units other than TFE units, crystallization of PTFE is suppressed to some extent, and tensile strength, tensile elongation, resistance to dielectric breakdown, creep resistance, etc. are improved.
• the fluororesin 1 has a thermal history of being heated to a melting point or higher at least once.
• the fluororesin 1 can be obtained by pulverizing cuttings generated when processing a primary molded body produced by heating to a melting point or higher into a secondary molded body such as an industrial part having a desired shape, or an unnecessary secondary molded body.
• the pulverization can be performed using a pulverizer or the like. After coarse pulverization, the material may be pulverized into fine particles.
• the heating can be exemplified by heating by firing required for producing a molded body.
• the melting point of the fluororesin 1 becomes lower than the melting point of the fluororesin 1 before being heated to or above its melting point.
• DSC differential scanning calorimetry
• the melting point of the fluororesin 1 before being heated to the melting point or higher is preferably 360° C. or lower, more preferably 355° C. or lower, and even more preferably 350° C. or lower.
• the melting point is preferably 100 to 360° C., more preferably 100 to 355° C., and even more preferably 150 to 350° C. When the melting point is within the above range, the mechanical strength of the obtained molded article tends to be improved.
• the melting point of the fluororesin 1 is preferably 335° C. or lower, and more preferably 330° C. or lower.
• the lower limit of the melting point is not particularly limited, but is preferably 100° C. or higher, and more preferably 150° C. or higher.
• the melting point is preferably 100 to 335° C., and more preferably 150 to 330° C. When the melting point is within the above range, the mechanical strength of the obtained molded article tends to be improved.
• the bulk density of fluororesin 1 is preferably 100 g/L or more, more preferably 105 g/L or more, and even more preferably 110 g/L or more.
• the bulk density is equal to or more than the lower limit, less air is carried in during the production of the molded body, which results in excellent deaeration properties and good fusion between powder particles. Furthermore, voids are less likely to remain in the resulting molded body, and the uniformity of the molded body is also likely to be improved.
• the average particle size of the fluororesin 1 is preferably from 1 to 500 ⁇ m, more preferably from 5 to 300 ⁇ m, and even more preferably from 5 to 100 ⁇ m. When the average particle size of the fluororesin 1 is within the above range, the uniformity of the fluororesin molded article is improved.
• the fluororesin 1 may be, for example, crushed pieces of a molded product obtained by molding a molding material containing PTFE obtained by suspension polymerization using a method including a step of heating the material to the melting point or higher.
• the PTFE obtained by suspension polymerization has a very high melt viscosity, and is non-melt moldable, which means that it cannot be molded by the general molding method of thermoplastic resins, such as extrusion molding, injection molding, etc. Therefore, when molding the PTFE produced by suspension polymerization (hereinafter also referred to as "molding powder"), the molding powder is filled into a mold, compression molded, and then fired.
• the molding powder is molded by first filling the molding powder into a mold at room temperature, compressing it to form a preform, and then heating it to the melting point of PTFE or higher to sinter it to form a primary molded body.
• the molding powder may be granulated as necessary and used as a granulated product.
• inorganic fillers and other optional components may be mixed during granulation.
• the primary molded body is then machined, such as by cutting, to produce a secondary molded body of a desired shape. Examples of secondary molded bodies include industrial components such as gaskets, linings, and insulating films, and square tanks that are exposed to strong acids and strong alkalis in the semiconductor industry.
• Cuttings and scraps generated when cutting a primary molded body into a secondary molded body, powder obtained by crushing the cuttings, powder obtained by crushing unnecessary secondary molded bodies, and other powders can be used as the fluororesin 1.
• the cuttings, etc. and the powders are collectively referred to as "crushed material.”
• the secondary molded body or the cuttings, etc. can be crushed by a crusher or the like. After coarse crushing, they may be finely ground. The volume of each crushed piece is, for example, 50 cm3 or less.
• Fluororesin 2 is a non-melt moldable fluororesin produced by emulsion polymerization, and has no thermal history of being heated above its melting point. The fact that the material "has no thermal history of being heated to or above its melting point” can be confirmed by differential scanning calorimetry (DSC).
• the emulsion polymerization method is a polymerization method in which a monomer is polymerized in an aqueous medium containing water to obtain a dispersion containing particles of the fluororesin 2 (hereinafter also referred to as a "second dispersion").
• emulsion polymerization is performed by a method in which a reaction liquid containing water, a polymerization initiator, and a surfactant is polymerized in the reaction liquid while the reaction liquid is stirred.
• the aqueous emulsion after emulsion polymerization may be used as the second dispersion, or a nonionic surfactant may be added to the aqueous emulsion to improve storage stability, and the aqueous dispersion may be used as the second dispersion.
• the content of the nonionic surfactant per 100 parts by mass of the fluororesin in the second dispersion is preferably 2 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.1 parts by mass or less. Examples of nonionic surfactants will be described later.
• the melting point of the fluororesin 2 is preferably 360° C. or lower, more preferably 355° C. or lower, and even more preferably 350° C. or lower.
• the lower limit of the melting point is not particularly limited, but is preferably 100° C. or higher, and more preferably 150° C. or higher.
• the melting point is preferably 100 to 360° C., more preferably 100 to 350° C., and even more preferably 150 to 350° C. When the melting point is within the above range, the mechanical strength of the obtained molded article tends to be improved.
• the content of fluororesin 2 relative to the total mass of the second dispersion is preferably 5 to 40 mass%, more preferably 7 to 35 mass%, and even more preferably 10 to 30 mass%.
• the average particle size of the fluororesin 2 contained in the second dispersion is preferably 0.05 to 0.5 ⁇ m, more preferably 0.08 to 0.45 ⁇ m, and even more preferably 0.10 to 0.35 ⁇ m. When the average particle size is within the above range, the emulsion stability is excellent.
• the fluororesin 2 preferably contains PTFE obtained by emulsion polymerization.
• a TFE monomer is homopolymerized in the reaction liquid, or a TFE monomer is copolymerized with a monomer other than TFE monomer in the reaction liquid to obtain a second dispersion in which PTFE particles are dispersed in a dispersion medium.
• a pressure of preferably 0.5 to 3.0 MPa is applied and a TFE monomer is emulsion-polymerized for preferably 1 to 20 hours to obtain a second dispersion.
• the nonionic surfactant may also be added.
• a dispersion may be obtained without using a fluorine-based surfactant by the methods described in WO 2021/085470, WO 2022/181662, etc.
• the amount of the anionic fluorine-containing emulsifier used in the emulsion polymerization step of TFE monomer is preferably 0.15 to 2.0 parts by mass, more preferably 0.2 to 1.0 part by mass, and even more preferably 0.2 to 0.5 part by mass, per 100 parts by mass of the PTFE produced.
• paraffin wax As the stabilizing aid, paraffin wax, fluorine-based oil, fluorine-based solvent, silicone oil, etc. are preferable, and paraffin wax is more preferable.
• the stabilizing aid may be used alone or in combination of two or more kinds.
• the paraffin wax may be liquid, semi-solid or solid at room temperature, but is preferably a saturated hydrocarbon having 12 or more carbon atoms.
• the melting point of the paraffin wax is preferably 40 to 65° C., more preferably 50 to 65° C.
• the amount of the stabilizing aid used is preferably 0.1 to 12 parts by mass, more preferably 0.1 to 8 parts by mass, per 100 parts by mass of the aqueous medium used.
• a water-soluble radical initiator or a water-soluble redox catalyst is preferably used.
• a persulfate such as ammonium persulfate or potassium persulfate; or a water-soluble organic peroxide such as disuccinic acid peroxide, bisglutaric acid peroxide, or tert-butyl hydroperoxide; is preferable.
• the polymerization initiator may be used alone or in combination of two or more. An oil-soluble initiator can also be used.
• disuccinic acid peroxide is more preferable.
• the amount of the polymerization initiator used is preferably 0.01 to 0.20 parts by mass, and more preferably 0.01 to 0.15 parts by mass, per 100 parts by mass of the PTFE to be produced.
• the standard specific gravity (SSG) of the PTFE contained in the second dispersion can be conceptually classified as high molecular weight PTFE when it is 2.14 or more and less than 2.22, and as low molecular weight PTFE when the SSG is 2.22 to 2.4. Since the physical properties of PTFE decrease when the molecular weight is low, the SSG is preferably 2.14 or more and less than 2.22, and more preferably 2.14 to 2.21.
• Anionic fluorine-containing emulsifier examples include fluorine-containing emulsifiers represented by general formula (1) (hereinafter, also referred to as "fluorine-containing emulsifier (1)").
• General formula (1) XCF 2 CF 2 (O) m CF 2 CF 2 OCF 2 COOA (In the formula, X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4 , and m is 0 or 1.)
• the fluorine-containing emulsifier (1) is preferred because of its excellent polymerization stabilizing effect on the PTFE particles.
• the above X is preferably a fluorine atom.
• the above m is preferably 1 in that the polymerization stability and the mechanical stability of the second dispersion are good.
• Specific examples of A include H, Li, Na, K, NH4 , etc.
• NH4 is preferred in that the fluorine-containing emulsifier (1) has good solubility in water and metal ion components are less likely to remain as impurities.
• Particularly preferred examples of the fluorine - containing emulsifier ( 1) are CF3CF2CF2CF2OCF2COONH4 and C2F5OCF2CF2OCF2COONH4 ( hereinafter referred to as EEA ), with EEA being more preferred.
• the fluorine-containing emulsifier (1) can be produced by fluorinating the corresponding ester of a non-fluorine-containing carboxylic acid or a partially fluorinated carboxylic acid by a known fluorination method such as a liquid phase fluorination method in which the ester is reacted with fluorine in a liquid phase, a fluorination method using cobalt fluoride, or an electrochemical fluorination method, hydrolyzing the ester bond of the resulting fluorinated ester, purifying it, and neutralizing it with ammonia.
• a known fluorination method such as a liquid phase fluorination method in which the ester is reacted with fluorine in a liquid phase, a fluorination method using cobalt fluoride, or an electrochemical fluorination method, hydrolyzing the ester bond of the resulting fluorinated ester, purifying it, and neutralizing it with ammonia.
• Nonionic fluorine-containing emulsifier examples of the nonionic surfactant to be blended in the aqueous emulsion obtained by emulsion polymerization include a nonionic surfactant represented by general formula (2) (hereinafter also referred to as “nonionic surfactant (2)”) and a nonionic surfactant represented by general formula (3) (hereinafter also referred to as “nonionic surfactant (3)").
• R 1 -ODH (In the formula, R1 is an alkyl group having 8 to 18 carbon atoms, O is an oxygen atom, and D is a polyoxyalkylene chain consisting of 5 to 20 oxyethylene groups and 1 to 2 oxypropylene groups.)
• R 2 -OEG (In the formula, R2 is an alkyl group having 6 to 18 carbon atoms, O is an oxygen atom, E is a polyoxyalkylene chain consisting of 1 to 3 oxybutylene groups and 5 to 20 oxyethylene groups, and G is a hydrogen atom or a methyl group.)
• the nonionic surfactants may be used alone or in combination of two or more kinds.
• the nonionic surfactant contained in the second dispersion is preferably one or more selected from the group consisting of nonionic surfactant (2) and nonionic surfactant (3), and two or more may be used in combination.
• Nonionic surfactant (2) and nonionic surfactant (3) may be combined.
• Nonionic surfactants are mixtures of multiple molecules with a certain chain length distribution and a mixture of isomers, and the chain length of the polyoxyalkylene chain represents the average chain length of multiple molecules.
• the number of oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain is the average value.
• the average number of oxyalkylene groups in each nonionic surfactant should be within the above-mentioned range.
• each numerical value is not limited to an integer.
• the number of carbon atoms in the alkyl group represented by R1 is preferably in the range of 8 to 18, more preferably 10 to 16.
• the number of carbon atoms in R1 is equal to or greater than the lower limit of the above range, the surface tension of the second dispersion liquid tends to be low and the wettability tends to be increased.
• the number of carbon atoms is equal to or less than the upper limit, the second dispersion liquid has excellent storage stability.
• the hydrophobic alkyl group has a branched structure in which the alkyl group is branched in the middle, it is preferable because it is easier to increase the wettability of the second dispersion.
• the alkyl group having a branched structure is preferably an alkyl group having a branch in the range from the carbon atom at the base of the alkyl group to the fifth carbon atom, and more preferably an alkyl group having a branch in the range from the carbon atom at the base of the alkyl group to the third carbon atom.
• the branched carbon atom may be a secondary carbon atom or a tertiary carbon atom, and a secondary carbon atom is preferable.
• Examples of the alkyl group having a branched structure include C10H21CH ( CH3 ) CH2- , C9H19CH ( C3H7 )- , and C6H13CH ( C6H13 ) -.
• the hydrophilic group D is a polyoxyalkylene chain consisting of 5 to 20 oxyethylene groups and 1 to 2 oxypropylene groups.
• the polyoxyalkylene chain consists of 7 to 12 oxyethylene groups and 1 to 2 oxypropylene groups
• the properties of the second dispersion become favorable.
• D contains an oxypropylene group
• the defoaming property is likely to be improved.
• the number of oxypropylene groups is 2 or less, the surface tension is low, the wettability is easily increased, and repellency during recoating is unlikely to occur, which is preferable.
• the oxypropylene group may be present between the polyoxyethylene groups, or may be bonded to the polyoxyethylene chain end.
• the defoaming property is easily improved.
• the defoaming property is more easily improved.
• the average number of oxyethylene groups in one molecule is preferably 5 to 20, and more preferably 7 to 12.
• the average number of oxyethylene groups in one molecule is equal to or more than the lower limit of the above range, good storage stability is likely to be obtained.
• the average number of oxyethylene groups in one molecule is equal to or less than the upper limit of the above range, good wettability is likely to be obtained.
• nonionic surfactant (2) commercially available nonionic surfactants having average molecular structures such as C13H27O ( C2H4O ) 8C3H6OH , C13H27O ( C2H4O ) 9C3H6OH , C13H27O ( C2H4O ) 10 (C3H6O)2H, and C16H27O(C2H4O ) 12 ( C3H6O ) 2H can be used .
• the content of nonionic surfactant (2) is preferably 2 to 12 parts by mass, more preferably 4 to 12 parts by mass, per 100 parts by mass of the fluororesin in the second dispersion. If it is equal to or greater than the lower limit of the above range, good storage stability is likely to be obtained. A high content of nonionic surfactant (2) is suitable for applications requiring thick application, but no improvement in performance is observed even if the content exceeds the upper limit of the above range, and for economic reasons, it is preferable to keep it below the upper limit of the above range.
• the number of carbon atoms in the alkyl group represented by R2 is preferably in the range of 6 to 18, more preferably 8 to 16, and even more preferably 10 to 14.
• the number of carbon atoms in the alkyl group is equal to or greater than the lower limit of the range, the surface tension of the second dispersion is likely to be low and the wettability is likely to be increased.
• the number of carbon atoms in the alkyl group is equal to or less than the upper limit of the range, the second dispersion is excellent in storage stability.
• the number of carbon atoms in the alkyl group is within the above range, the wettability and storage stability are good.
• the alkyl group represented by R2 has a branched structure, it is preferable since the wettability of the second dispersion liquid can be more easily increased.
• the branched carbon atom may be a secondary carbon atom or a tertiary carbon atom, and a secondary carbon atom is preferable.
• Examples of the alkyl group having a branched structure include C10H21CH ( CH3 ) CH2- , C9H19CH ( C3H7 ) - , C6H13CH (C6H13 ) -, CH( CH3 ) 2CH2CH ( CH3 ) 2CH2CH ( CH ( CH3 ) 2CH2- , and the like.
• the alkyl group represented by R2 may have up to 10% of the hydrogen atoms in the alkyl group substituted with a halogen element such as a fluorine atom, a chlorine atom, a bromine atom, etc.
• the alkyl group may also contain 1 to 2 unsaturated bonds.
• E in the general formula (3) is a polyoxyalkylene chain consisting of 1 to 3 oxybutylene groups and 5 to 20 oxyethylene groups.
• the number of oxybutylene groups is preferably 1 to 2.5, more preferably 1 to 2.
• the defoaming property, wettability and viscosity properties tend to be good.
• the viscosity increase of the second dispersion is suppressed, and good stability is likely to be obtained.
• the properties such as viscosity, stability, defoaming property and wettability are good, which is preferable.
• the oxybutylene group may be branched or linear, with branched being preferred.
• Examples of oxybutylene groups include -CH2- CH( C2H5 )-O-, -CH ( C2H5 )CH2 - O-, -CH( CH3 ) -CH(CH3)-O-, -CH2CH2-CH(CH3 ) -O- , -CH2CH2CH2CH2 - O- , and the like . Of these, -CH2 - CH( C2H5 )-O-, -CH( C2H5 ) CH2 - O- and -CH2CH2 - CH ( CH3 )-O- are preferable.
• Examples of raw materials for the oxybutylene group include various butylene oxides, and specific examples include 1,2-butylene oxide, 2,3-butylene oxide, tetrahydrofuran, and methyloxetane.
• the number of oxyethylene groups in the polyoxyalkylene chain is 5 to 20, preferably 6 to 15, and more preferably 7 to 13.
• the storage stability of the second dispersion tends to be good.
• the wettability tends to be good.
• the properties such as viscosity, stability, defoaming property, and wettability are good, which is preferable.
• the oxybutylene groups in the polyoxyalkylene chain may have a block structure or a random structure.
• the oxybutylene group may be present in any portion of the polyoxyalkylene chain, but is preferably present in the range from the R 2 -O- group side to up to 70% of the total length of the polyoxyalkylene chain, and more preferably present in the range from the R 2 -O- group side to up to 50% of the total length of the polyoxyalkylene chain.
• the portion of the polyoxyalkylene chain bonded to the R 2 -O- group is preferably an oxybutylene group, more preferably a polyoxybutylene chain consisting of 1 to 2 oxybutylene groups.
• the portion of the polyoxyalkylene chain bonded to the G group is preferably an oxyethylene group, more preferably a polyoxyethylene chain consisting of 5 to 20 oxyethylene groups.
• Polyoxyalkylene chains having these preferred structures are preferred because they have better properties such as viscosity, stability, antifoaming property, and wettability.
• G is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.
• the nonionic surfactant (3) can be obtained by addition reaction of butylene oxide and ethylene oxide with a higher alcohol by a known method. Butylene oxide and ethylene oxide may be mixed and reacted simultaneously, butylene oxide may be reacted first and then ethylene oxide, or ethylene oxide may be reacted first and then butylene oxide. The method of reacting butylene oxide first and then ethylene oxide is preferred.
• nonionic surfactant ( 3 ) examples include C13H27OCH2CH ( C2H5 )O (C2H4O ) 8H , C10H21CH ( CH3 ) CH2OCH2CH ( C2H5 ) O ( C2H4O ) 8 H , C10H21CH ( CH3 ) CH2OCH ( C2H5 ) CH2O ( C2H4O ) 8H , C12H25OCH2CH ( C2H5 )O( C2 H4O ) 8H , C8H17 OCH2CH ( C2H5 )O ( C2H4O ) 10 H , C12H25OCH2CH ( C2H5 ) O ( C2H4O ) 10H , C13H27OCH2CH ( C2H5 )O( C2H4O ) 11H , C13H27OCH2CH2 OCH2CH ( C2H5 )O( C2H4O ) 11
• the content of nonionic surfactant (3) is preferably 0.1 to 12 parts by mass, more preferably 0.5 to 11 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the fluororesin in the second dispersion.
• the content is equal to or greater than the lower limit of the above range, good storage stability is likely to be obtained.
• cracks are less likely to occur in the fluororesin coating film, and repellency is less likely to occur.
• a high content of nonionic surfactant (3) is suitable for applications where a thick coating is required, but no improvement in performance is observed even if the content exceeds the upper limit of the above range, and for economic reasons, it is preferable that the content is equal to or less than the upper limit of the above range.
• the number of oxybutylene groups per molecule of the nonionic surfactant is preferably 0.5 to 2, more preferably 0.7 to 1.7, and even more preferably 0.9 to 1.5.
• the nonionic surfactant (2) and the nonionic surfactant (3) may be added separately.
• a mixture containing the nonionic surfactant (3) and the nonionic surfactant (2) produced as a by-product during the preparation of the nonionic surfactant (3) may also be used.
• the second dispersion contains water as a dispersion medium for the fluororesin particles.
• This water may be water contained in the aqueous emulsion obtained by emulsion polymerization, or it may be water prepared separately from the water in the aqueous emulsion.
• the second dispersion may contain one or more of the following as required: a pH adjuster (e.g., ammonia, etc.), an anionic surfactant, a polyethylene oxide-based thickener, a polyurethane-based thickener, a thixotropic agent, a silicone-based wettability improver, a fluorine-based wettability improver, a preservative, etc.
• a pH adjuster e.g., ammonia, etc.
• one or more of the following may be blended: water-soluble organic solvents, organic solvents (e.g., toluene, xylene, etc.), pigments (e.g., titanium oxide, iron oxide, carbon black, cobalt blue, etc.), glass powder, hollow glass beads, colorants (e.g., graphite particles, silica particles, mica or titanium oxide-coated mica powder, etc.).
• organic solvents e.g., toluene, xylene, etc.
• pigments e.g., titanium oxide, iron oxide, carbon black, cobalt blue, etc.
• glass powder e.g., glass powder, hollow glass beads, colorants (e.g., graphite particles, silica particles, mica or titanium oxide-coated mica powder, etc.).
• the fluororesin composition contains a fluororesin 1 and a fluororesin 2.
• the composition may contain one or more solid components other than the fluororesin 1 and the fluororesin 2.
• solid components include solid components used in the production process of fluororesin 1, solid components used in the production process of fluororesin 2, and solid components added after the production of fluororesin 1 and fluororesin 2.
• specific examples include inorganic fillers, pigments (for example, titanium oxide, iron oxide, carbon black, cobalt blue, etc.), colorants (for example, graphite particles, silica particles, mica or titanium oxide-coated mica powder, etc.), and the above-mentioned additives.
• inorganic fillers include reinforcing fibers (glass fibers, carbon fibers, etc.), glass powder, bronze powder, graphite powder, hollow glass beads, and the like.
• the content of other solid components is preferably 70 mass % or less, more preferably 60 mass % or less, and even more preferably 50 mass % or less, based on the total mass of the solid contents of the fluororesin composition. It may be zero.
• a powdered fluororesin composition is used for compression molding.
• Examples of a method for producing a powdered fluororesin composition include the following embodiments (1) to (4), with embodiment (4) being preferred.
• (1) Powdered fluororesin 1 and powdered fluororesin 2 are mixed in a dry state.
• Powdered fluororesin 1 and a dispersion liquid in which fluororesin 2 is dispersed are mixed, and the solid in the resulting mixture is powderized.
• the dispersion liquid in which the fluororesin 1 is dispersed is mixed with powdered fluororesin 2, and the solid in the resulting mixture is pulverized.
• (4) The dispersion in which fluororesin 1 is dispersed and the dispersion in which fluororesin 2 is dispersed are mixed, and the solid in the resulting mixture is pulverized.
• the dispersion in which the fluororesin 1 is dispersed is preferably a dispersion obtained by mixing the powdered fluororesin 1 produced by the above-mentioned production method with a water-soluble organic solvent.
• the water-soluble organic solvent is preferably one or more water-soluble organic solvents selected from the group consisting of aprotic water-soluble organic solvents and alcohols.
• the alcohols may have an amino group or an alkoxy group as a substituent.
• aprotic water-soluble organic solvent acetone, tetrahydrofuran, or acetonitrile is preferred.
• methanol, ethanol, propanol, isopropyl alcohol, or 1-methoxy-2-propanol is preferred.
• water-soluble organic solvent isopropyl alcohol is more preferred.
• water-soluble organic solvent one type may be used alone, or two or more types may be used in combination.
• the content of fluororesin 1 relative to the total mass of the first dispersion is preferably 3 to 70 mass%, more preferably 5 to 65 mass%, and even more preferably 10 to 60 mass%.
• the second dispersion liquid is preferable as the dispersion liquid in which the fluororesin 2 is dispersed.
• the powdered fluororesin 2 obtained by separating the fluororesin 2 from the solvent in the second dispersion liquid by filtration, drying, etc. may be used.
• the mixture is stirred to aggregate the fluororesin 1 and the fluororesin 2, and then the aggregate and the dispersion medium are separated into solid and liquid by filtration, followed by drying, to obtain a powdery fluororesin composition.
• the aggregate obtained by solid-liquid separation may be washed.
• the washing solvent water or an aqueous solution is preferable.
• the aggregate contains a water-soluble organic solvent, it is preferable to use the washing solvent after adjusting the pH to a pH that can remove the water-soluble organic solvent.
• the aggregate may be dried by vacuum drying or by drying at normal pressure, and is preferably dried at a temperature equal to or lower than the melting point of the fluororesin for 6 hours or more.
• the glossiness of the molded product can be adjusted by adjusting the conditions of the aggregation step in which the mixture is stirred to obtain the aggregates. For example, increasing the temperature of the mixture in the aggregation step tends to decrease the gloss. Also, increasing the stirring strength in the aggregation step tends to increase the gloss.
• the stirring strength can be adjusted by the rotation speed of the stirring blade, the shape of the stirring blade, and the number and shape of the baffle plates. These adjustment methods may be combined.
• the combined content of fluororesin 1 and fluororesin 2 relative to the total mass of the mixture is preferably 10 to 50 mass%, more preferably 12 to 45 mass%, and even more preferably 15 to 35 mass%.
• the combined content of fluororesin 1 and fluororesin 2 is equal to or greater than the lower limit of the above range, fluororesin 1 and fluororesin 2 tend to aggregate and are more likely to undergo solid-liquid separation.
• the combined content of fluororesin 1 and fluororesin 2 is equal to or less than the upper limit of the above range, mixing of fluororesin 1 and fluororesin 2 is more likely to be promoted.
• the content of the water-soluble organic solvent relative to 100 parts by mass of water in the mixture is preferably 1 to 150 parts by mass, more preferably 3 to 140 parts by mass, and even more preferably 5 to 130 parts by mass.
• the proportion of fluororesin 1 relative to the total mass of fluororesin 1 and fluororesin 2 is 40 mass% or more, preferably 45 mass% or more, more preferably 50 mass% or more, even more preferably 52 mass% or more, and particularly preferably 55 mass% or more.
• the proportion of fluororesin 1 is equal to or greater than the lower limit of the above range, it is easy to adjust the gloss of the molded body to 15% or more.
• the upper limit is not particularly limited, and is, for example, less than 100 mass%.
• the molded article of the present invention can be obtained by a method of compression molding the fluororesin composition and firing the same. Specifically, the powdered fluororesin composition is placed in a mold, compressed and molded under pressure to obtain a preform, and the preform is fired to obtain a primary molded article.
• the shape of the primary molded article is not particularly limited. For example, it may be a block shape such as a cylindrical or polygonal column shape.
• the fluororesin composition When the fluororesin composition is compression molded, it is preferable to apply a pressure of 100 to 350 kg/cm 2 .
• the firing temperature after the preforming is preferably 360 to 380°C.
• the obtained primary molded body may be processed by cutting or other processes to produce a secondary molded body of a desired shape.
• Examples of uses for the secondary molded body include seals, packing, rollers, sockets, and joints.
• the fluororesin molded article of the present invention may be the above-mentioned primary molded article or the above-mentioned secondary molded article.
• the glossiness of the fluororesin molded article of the present invention is 15% or more, preferably 18% or more, and more preferably 20% or more.
• the gloss level is equal to or higher than the lower limit, good compressive strength and compressive creep resistance can be obtained. There is no particular upper limit to the gloss level.
• the compressive strength of the fluororesin molded article of the present invention is preferably 3 MPa or more in compressive strength (1% deformation) and 12 MPa or more in compressive strength (10% deformation). More preferably, the compressive strength (1% deformation) is 3.3 MPa or more and the compressive strength (10% deformation) is 13 MPa or more, and even more preferably, the compressive strength (1% deformation) is 3.5 MPa or more and the compressive strength (10% deformation) is 14 MPa or more.
• the upper limit of the compressive strength is not particularly limited.
• the compressive strength in this specification is a value obtained by the measurement method described in the Examples.
• the compression creep properties of the fluororesin molded article of the present invention are preferably such that the compression creep (deformation) is 15% or less and the compression creep (permanent deformation) is 12% or less. More preferably, the compression creep (deformation) is 13% or less and the compression creep (permanent deformation) is 11% or less, and even more preferably, the compression creep (deformation) is 10% or less and the compression creep (permanent deformation) is 10% or less.
• the lower limit of the compression creep is not particularly limited.
• the compression creep in this specification is a value obtained by the measurement method described in the Examples.
• a laser diffraction/scattering type particle size distribution measuring device (LA-920 measuring device, manufactured by Horiba, Ltd.) was used to disperse the powdered fluororesin in water, and the particle size distribution was measured and calculated based on the number of particles.
• SSG Standard Specific Gravity
• [Glossiness] 345 g of the fluororesin composition was placed in a mold having an inner diameter of 7.3 mm and pressed at 320 kg/cm 2 to obtain a preform. This preform was baked at 380° C. for 2 hours to obtain a fluororesin molded product.
• the gloss level was evaluated by measuring a sheet-like molded product having a thickness of 0.5 mm obtained by skiving the obtained fluororesin molded product.
• the specular gloss was measured at an incidence angle of 60° in accordance with JIS Z 8741 using a PG-IIM manufactured by Nippon Denshoku Industries Co., Ltd.
• Test specimens were prepared as follows. 6.5 g of the fluororesin composition was placed in a mold having an inner diameter of 12.95 mm and pressed at 320 kg/ cm2 to obtain a preform. This preform was baked at 380°C for 2 hours to obtain a test piece having a diameter of 12.7 mm and a height of 25.4 mm.
• the compressive strength was measured using a Tensilon universal material testing machine (RTF-1350 manufactured by Orientec Co., Ltd.) in accordance with ASTM D695. Compressive strength (1% deformation) indicates the compressive stress when the strain is 1%. The larger this value, the better the compressive strength. Compressive strength (10% deformation) indicates the compressive stress when the strain is 10%. The larger this value, the better the compressive strength.
• Test specimens were prepared as follows. 6.5 g of the fluororesin composition was placed in a mold having an inner diameter of 12.95 mm and pressed at 320 kg/ cm2 to obtain a preform. This preform was baked at 380°C for 2 hours and processed into a test piece having a diameter of 12.7 mm and a height of 12.7 mm.
• the compression creep property was measured in accordance with ASTM D621 using a creep tester (145-SV-3 manufactured by Yasuda Seiki Seisakusho). Specifically, a load of 13.7 MPa was applied to the test piece at 24°C, and the strain after 10 seconds was considered to be the initial deformation.
• Example 1 is an embodiment, and Examples 2 and 3 are comparative examples.
• Powdered fluororesin 1 was produced by the following method. Powder (molding powder, melting point before heating 343°C) made of unsintered PTFE homopolymer obtained by suspension polymerization was preformed and sintered to obtain a molded body. The obtained molded body was pulverized to obtain PTFE with an average particle size of 40 ⁇ m or less. The melting point of the obtained PTFE was 329°C and the bulk density was 394 g/L. The obtained PTFE was not melt-moldable, since there was no temperature at which the melt flow rate was 0.1 to 1000 g/10 min at a temperature 20° C. or more higher than the melting point of the resin under a load of 49 N.
• a dispersion of fluororesin 2 was produced by the following method.
• EEA was used as an anionic fluorine-containing emulsifier (1).
• 36 g of EEA, 555 g of paraffin wax (melting point 55°C), and 61.3 L of deionized water were charged into a 100 L stainless steel autoclave equipped with a baffle plate and a stirrer. After the inside of the autoclave was replaced with nitrogen, the pressure was reduced, and TFE monomer was introduced and heated to 62°C while stirring.
• TFE monomer was injected until the internal pressure reached 1.765 MPa, and 26.3 g of disuccinic acid peroxide (concentration 80% by mass, the remainder being water) was dissolved in 1 L of warm water at about 70°C and injected.
• the content of PTFE relative to the total mass of the second dispersion was about 25.0 mass%, and the content of EEA relative to 100 mass parts of PTFE was 0.40 mass parts.
• the average particle size of the PTFE particles in the second dispersion was 0.26 ⁇ m.
• the standard specific gravity (SSG) of PTFE was 2.21.
• the melting point of the obtained PTFE was 337° C.
• the obtained PTFE was not melt-moldable, since there was no temperature at which the melt flow rate was 0.1 to 1000 g/10 min at a temperature 20° C. or more higher than the melting point of the resin under a load of 49 N.
• a powdered fluororesin composition was produced by the following method.
• a first dispersion was prepared in advance by mixing 200 g of the powdered fluororesin 1 (PTFE) obtained above and 200 g of isopropanol (IPA).
• PTFE powdered fluororesin 1
• IPA isopropanol
• the amount of fluororesin 1 was 50.0 mass % based on the total mass of the first dispersion.
• the mass ratio of PTFE in the second dispersion to the powder of fluororesin 1 (PTFE) was 1:1.
• the mass ratio of IPA in the first dispersion to water in the second dispersion was 12: 88.
• an aggregation step was carried out. That is, the mixture was stirred at 680 rpm for 10 minutes using a stirrer at 25°C and normal pressure to aggregate the solid content in the mixture. Then, the mixture was filtered using a sieve to separate the aggregates from the solvent. The aggregates were washed with a large amount of water, placed in a vat, vacuum dried at 25°C for 8 hours or more, and dried at 200°C for 10 hours or more to obtain a powdered fluororesin composition. The proportion of fluororesin 1 relative to the total mass of fluororesin 1 and fluororesin 2 contained in the obtained fluororesin composition was 50 mass %.
• the obtained fluororesin composition was placed in a mold having a predetermined shape and pressed at 320 kg/ cm2 to obtain a preform. This preform was baked at 380° C. for 2 hours to obtain a fluororesin molded article (primary molded article) of Example 1.
• Example 1 the molding powder (powder made of unsintered PTFE homopolymer obtained by suspension polymerization) used in Example 1 was used instead of the fluororesin composition. Except for this, a fluororesin molded article (primary molded article) was produced in the same manner as in Example 1 and evaluated.
• Example 2 In Example 1, powder of fluororesin 1 was used instead of the fluororesin composition. Except for that, the same procedure as in Example 1 was used to attempt the production of a fluororesin molded product, but the adhesion between the fluororesin particles was insufficient and no molded product was obtained. Therefore, the gloss, compressive strength and compressive creep tests were not performed.
• Example 3 powder of fluororesin 2 was used in place of the fluororesin composition. That is, when producing a powdered fluororesin composition, the first dispersion was not used, and fluororesin 2 in the second dispersion was aggregated and filtered, and the obtained aggregate was vacuum-dried at 25° C. for 8 hours or more and then dried at 200° C. for 10 hours or more to obtain powdered fluororesin 2. Other than that, a fluororesin molded article was produced in the same manner as in Example 1. When the obtained fluororesin molded article was compressed in a compression test, numerous voids were generated.
• the fluororesin molded product of Example 1 had a gloss level of 15% or more, and despite containing fluororesin 1, a pulverized sintered suspension-polymerized PTFE, as a raw material, it exhibited compressive strength and compressive creep properties comparable to those of the fluororesin molded product of Reference Example 1, which was made from unsintered suspension-polymerized PTFE.

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